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Not rolling back malaria

Malaria and the DDT Story
Richard Tren and Roger Bate
Institute of Economic Affairs, 2000

This is a short “Occasional Paper” of about 100 pages, including Introduction and Bibliography, which I read without reviewing when I received it . After reading Robert Ross’s Memoirs, Honigsbaum’s The Fever Trail and Rocco’s The Miraculous Fever Tree, books about cinchona/quinine and Sallares’ Malaria and Rome, I thought I had better re-read it with more attention.

DDT (Dichloro-diphenyl-trichloro-ethane) is the safest, most efficient and cheapest insecticide used to eradicate Anopheles, the mosquito that transmits malaria from person to person. There are three species of malarial parasites in humans, Plasmodium vivax, Plasmodium malariae and Plasmodium falciparum (a pedant would add a very rare fourth), of which falciparum is by far the most deadly and essentially the cause of the problem under discussion. Since it is estimated that a million people die of malaria every year (p. 13) the evidence given here is that, beginning in the early 1970s, the withdrawal of DDT as an weapon in the battle against malaria has resulted in the loss of lives that may be numbered by the million. In brief, where malaria has been eradicated, it is where DDT was used, in Europe, N. America and the Caribbean. Where it was almost eradicated and has made a comeback, markedly in Ceylon and India, is where DDT was first used, and then its use discontinued. If true, the delivery of this message is rather muffled by a certain lack of indignation on the part of the authors.

Environmental activists – e.g., the World Wildlife Fund, Greenpeace etc. – are the villains here, and it is difficult not to include Rachel Carson whose Silent Spring, demonizing DDT, was published in 1962. Despite the evidence, produced before and after this date, of the harmlessness of DDT to humans and its beneficent effect, no one amongst them seems to have changed their minds, or altered their hostility to it, while tolerating the introduction of even more dangerous, and expensive, insecticides, such as the organophosphate Malathion (p. 46). Another villain is (or was) William Ruckelhaus, head of the US Environmental Protection Agency (EPA) “whose refusal to accept the scientific advice offered, most certainly contributed to death in malarial countries (p. 46).” Also on the list must be the ex-Norwegian PM, Mrs Brundtland, hard-line environmentalist and head of the WHO, whose “Roll Back Malaria” programme does not promote mosquito control. Two more DDT saboteurs are Physicians for Social Responsibility (PSR) and Pesticide Action Network (PAN). Prohibitions on DDT, indeed on all persistent organic pollutants (POPs), began to be put in place by such means as the United Nations Environmental Programme (UNEP), and various Inter-governmental Negotiating Committees (INCs), where the countries most affected were too poor to afford to send sufficient delegates (p. 50). The idiotic “Precautionary Principle” has also been destructively invoked (p. 59-61) and is refuted by the authors, though they fail to use the concept of “trade-off” – the enormous life-saving benefits of DDT against the comparatively small, hypothetical, and unproved risks.

Another feature of the 1970s, when this was happening, was concern about the rise in world population. There is more than a suspicion that malaria eradication was seen by some as merely to make the problem worse. It might be more unkind to keep people from dying from malaria, so that they could die more slowly from starvation, ran one argument (p. 41).

Though DDT resistance in Anopheles (the malaria-transmitting mosquito) does occur (one pretext for discontinuing its use), it has been noted that it still remains Anopheles-repellent, a useful feature in consideration of the fact that it is usually sprayed within dwellings, where it has in any case minimal effect environmentally (p. 47). DDT is, in fact, still effective in most places and is much cheaper than any other insecticide (p. 69), despite efforts by Greenpeace to close down production in India (p. 54).

Ignoring protests from more than 350 scientists and physicians (p. 62), the WHO and other organizations have rejected mosquito eradication, directing their efforts only to curing the sufferers by quinine and synthetic drugs and hoping, sooner or later, to protect everyone by vaccines which have been “just around the corner” for several decades (p. 33). This has been the policy since the 1970s; before then, most research went into insecticides; afterwards into drugs and vaccines (p. 92n).

The authors do not discuss the virtues of a two-prong attack, i.e., to reach the goal of breaking the cycle of infection by reducing simultaneously both the numbers of infected humans (by medication) and the numbers of Anopheles (by DDT). Obviously having both low is more likely to break the cycle than lowering only one. Fortunately, relapses do not occur in falciparum malaria, the most dangerous kind, though relapses of vivax and malariae in “cured” humans will continue to provide occasional opportunities for transmission by surviving mosquitoes, an argument for concentrating on their complete eradication.

Such was the situation in 2000. I do not think it has changed much since then.

8 comments to Not rolling back malaria

  • Aaron

    Very interesting post, Findlay. Are you this guy?

    “Dunachie & Fletcher (1969) injected chicken eggs with DDT or TDE”

    What about the studies showing a significant effect on raptors, especially Lincer’s 1975 study on American Kestrels? It showed an inverse relationship between DDE (a DDT metabolite) concentrations and eggshell thickness.

  • Findlay Dunachie

    Yes, I was. We could inject an awful lot of DDT into fertilised hen’s egg yolk and all the chicks hatched OK. If they were fed, they survived, but we couldn’t keep them long (expense, you know). And we couldn’t starve them, but if their yolk had been used up, it would would probably have done them in. We tried a lot of other insecticides and herbicides. The worst was paraquat; eggs didn’t develop at all after very little was put in. But it was the only water-soluble herbicide.

  • bil.

    For more in a similar vein, I would recommend some of the books of Thomas R. Degregori. I was fortunate enough to have him as one of my economics professors, and it was a very enlightening experience.

  • Aaron


    I find the DDT debate very interesting – it says a lot about out society. You seem to have a lot of experience in this area. It’s pretty commonly shown that DDT has almost no effect on gallinaceous birds, but I’d be interested in hearing your thoughts on the raptor studies.

  • Funny your comments on Paraquat, you should dig up a book/paper by Prasanna Srinivasan called “Paraquat: A unique contributor to agriculture and sustainable development”, published last November. It carries a pretty solid overview of the massive economic importance of that particular herbicide for the Developing world.

  • John Elliot

    This story has had a bit of a run here in Australia. Someone, I forget who, wrote in and said they had worked on anti malaria programmes in Kenya and that mosquito resistance to DDT was inevitable anyway, even if DDT had not been banned. Your post, as I understand it, says that DDT resistance is not a problem. Is that correct? Also, if DDT was banned before mosquito resistance developed are we still not likely to see resistance develop if the use of DDT is resumed. From my limited experience of agriculture every insect or parasite seems to develop chemical resistance. Of course, my queries in no way justify the banning of DDT in the first place.

    Could you comment, please.

  • bruce

    As I understand it DDT works more as a repellent rather than an insecticide. The idea behind house spraying was that the mosquitos would rest on the walls before feeding. This is important since the parasite has to incubate in the mosquito for a few days. So the insecticide should kill before the mosquito could bite. A study in Belize found in homes sprayed with deltamethrin the mosquitos would enter a house and bite. In a house treated with DDT the mosquitos would enter and leave without biting. So DDT seems to block the feeding response of mosquitos.

  • Findlay Dunachie

    John Elliot! Please. You must read the book/monograph. That’s what the review is for. The post by Bruce also seems helpful and it does seem to be a fact that DDT is an insect-repellent even to insects that have evolved resistance. You could also search for publications by Roger Bate: I have seen something by him on the subject of malaria, I think on National Review Online.